From: Florian Westphal fw@strlen.de

mainline inclusion from mainline-v5.5-rc1 commit ca58fbe06c54795f00db79e447f94c2028d30124 category: bugfix bugzilla: NA CVE: CVE-2021-20177

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At this time, NF_HOOK_LIST() macro will iterate the list and then calls nf_hook() for each individual skb.

This makes it so the entire list is passed into the netfilter core. The advantage is that we only need to fetch the rule blob once per list instead of per-skb.

NF_HOOK_LIST now only works for ipv4 and ipv6, as those are the only callers.

v2: use skb_list_del_init() instead of list_del (Edward Cree)

Signed-off-by: Florian Westphal fw@strlen.de Acked-by: Edward Cree ecree@solarflare.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Conflicts: include/linux/netfilter.h net/netfilter/core.c [yyl: adjust context] Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: Yue Haibing yuehaibing@huawei.com Reviewed-by: Jason Yan yanaijie@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- include/linux/netfilter.h | 41 +++++++++++++++++++++++++++++---------- net/netfilter/core.c | 20 +++++++++++++++++++ 2 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h index 9460a5635c90..8bf57abee9e4 100644 --- a/include/linux/netfilter.h +++ b/include/linux/netfilter.h @@ -183,6 +183,8 @@ extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS]; int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state, const struct nf_hook_entries *e, unsigned int i);

+void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state, + const struct nf_hook_entries *e); /** * nf_hook - call a netfilter hook * @@ -295,17 +297,36 @@ NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct list_head *head, struct net_device *in, struct net_device *out, int (*okfn)(struct net *, struct sock *, struct sk_buff *)) { - struct sk_buff *skb, *next; - struct list_head sublist; - - INIT_LIST_HEAD(&sublist); - list_for_each_entry_safe(skb, next, head, list) { - skb_list_del_init(skb); - if (nf_hook(pf, hook, net, sk, skb, in, out, okfn) == 1) - list_add_tail(&skb->list, &sublist); + struct nf_hook_entries *hook_head = NULL; + +#ifdef CONFIG_JUMP_LABEL + if (__builtin_constant_p(pf) && + __builtin_constant_p(hook) && + !static_key_false(&nf_hooks_needed[pf][hook])) + return; +#endif + + rcu_read_lock(); + switch (pf) { + case NFPROTO_IPV4: + hook_head = rcu_dereference(net->nf.hooks_ipv4[hook]); + break; + case NFPROTO_IPV6: + hook_head = rcu_dereference(net->nf.hooks_ipv6[hook]); + break; + default: + WARN_ON_ONCE(1); + break; } - /* Put passed packets back on main list */ - list_splice(&sublist, head); + + if (hook_head) { + struct nf_hook_state state; + + nf_hook_state_init(&state, hook, pf, in, out, sk, net, okfn); + + nf_hook_slow_list(head, &state, hook_head); + } + rcu_read_unlock(); }

/* Call setsockopt() */ diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 93aaec3a54ec..3f0bdc728f89 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -536,6 +536,26 @@ int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state, EXPORT_SYMBOL(nf_hook_slow);

+void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state, + const struct nf_hook_entries *e) +{ + struct sk_buff *skb, *next; + struct list_head sublist; + int ret; + + INIT_LIST_HEAD(&sublist); + + list_for_each_entry_safe(skb, next, head, list) { + skb_list_del_init(skb); + ret = nf_hook_slow(skb, state, e, 0); + if (ret == 1) + list_add_tail(&skb->list, &sublist); + } + /* Put passed packets back on main list */ + list_splice(&sublist, head); +} +EXPORT_SYMBOL(nf_hook_slow_list); + int skb_make_writable(struct sk_buff *skb, unsigned int writable_len) { if (writable_len > skb->len)